The cytoplasms of the amphibian egg, when spawned for fertilization, contain information which serves to regulate the pattern of early embryonic development. The biochemical identity of that information, and the manner in which it is employed (at the molecular level) is not yet understood. The present research program will employ maternal effect mutations in an amphibian, the Mexican axolotl, as an experimental system. This organism has been maintained in the laboratory for over 50 years, and is, to a large extent, genetically defined. A small number of maternal effect mutations which act through altering the egg cytoplasm is available. These will be employed in an attempt to characterize specific regulatory molecules. By comparison of the mutant eggs with normal eggs, and by employing various bio-assays, the products of the mutant genes will be identified. Comparisons of macromolecular synthesis in normal and mutant eggs will be carried out in an attempt to determine how the regulatory molecules which are produced by the wild type alleles act to control the pattern of early embryogenesis.